Exploring the novel indigenous strains for degrading the crude oil contaminants in soil sample

Abstract

Soil hydrocarbon pollution often causes the crop quality and safety issue. Therefore, a high priority is given to exploring the novel bacterial strain to sustainable green agricultural food products. Two novel crude oil-degrading bacteria were screened from the local oil-contaminated soil, which exhibited a good emulsifying capacity in their oil spreading test, showing their most clearing zone on the oil covering petri dish. Glycolipid bio-surfactant was identified by the thin-layer chromatography analysis. Gas chromatography and ultraviolet spectrophotometer (UV) methods were used to evaluate the degradation degree of alkanes and aromatic hydrocarbons in crude oil. The biodegradation ability of a single strain was inferior to mixed strains. The latter revealed that the degradation of the crude oil was 92% and 85%, respectively, when cultured at 32 °C, 150 rpm for 20 days. The hardest degraded isoprenoid alkane (pristane) could easily be degraded by these mixed strains. The effect of cadmium (Cd) on the growth of isolated strains was also studied, and the results demonstrate that crude oil-degrading bacteria isolated in the present study have shown strong endurance to Cd2+ (IC50 were 228.80 mg L−1 and 97.74 mg L−1) for Pseudomonas aeruginosa Dut-lxm0725 and Rhodococcus erythropolis Dut-lxm1018 strains, respectively. The above results suggest that present wild strains could have a good application prospect in bioremediation of crude oil-contaminated soil.